Ether compounds and related compositions

ABSTRACT

In some embodiments, a compound has the formula (I) where: R 1  and R 2  are alkyl or, together with the carbon atom to which they are attached, cycloalkyl; R 3 , R 4  and R 5  are H or alkyl (formula II); R 6  is alkyl or where: R 7  and R 8  are H, alkyl or, together with the carbon atom to which they are attached, cycloalkyl; R 9  is H or alkyl; X is alkylene or is absent; and p is 0, 1, 2 or 3; and m and n are 0, 1, 2 or 3 provided that m is 0 when R 4  and R 5  are H. The compound is suitable for use as a base stock which provides low volatility for a given viscosity profile. The compound may be used in a lubricant composition for an internal combustion engine.

The present invention relates, in part, to compounds which may be usedas base stocks, in particular as base stocks which have a low volatilityfor a given viscosity profile, and which are suitable for use in alubricant composition for an internal combustion engine. Base oilscomprising said compounds and lubricant compositions comprising saidbase oils are also provided.

BACKGROUND

Lubricating compositions generally comprise a base oil of lubricatingviscosity together with one or more additives to deliver propertiesincluding for example, reduced friction and wear, improved viscosityindex, detergency, and resistance to oxidation and corrosion. Alubricant base oil may comprise one or more lubricating base stocks.

Lubricant base stocks used in automotive engine lubricants are generallyobtained from petrochemical sources, for example they may be obtained asthe higher boiling fractions isolated during the refining of crude oilor as the products of chemical reactions of feedstocks frompetrochemical sources. Lubricant base stocks can also be made fromFischer-Tropsch wax.

Lubricant base stocks may be classified as Group I, II, III, IV and Vbase stocks according to API standard 1509, “ENGINE OIL LICENSING ANDCERTIFICATION SYSTEM”, 17^(th) Edition, Annex E (October 2013 withErrata March 2015), as set out in Table 1.

TABLE 1 Saturated hydrocarbon Sulphur content (% by Viscosity contentweight) Index (% by weight) ASTM D2622, D4294, ASTM Group ASTM D2007D4927, D3120 or D1552 D2270 I <90 and/ >0.03 and ≥80 and or <120 II ≥90and ≤0.03 and ≥80 and <120 III ≥90 and ≤0.03 and ≥120 IVPolyalphaolefins V all base stocks not in Groups I, II, III or IV

Group I base stocks are typically manufactured by known processesincluding, for example, solvent extraction and solvent dewaxing, orsolvent extraction and catalytic dewaxing. Group II and Group III basestocks are typically manufactured by known processes including, forexample, catalytic hydrogenation and/or catalytic hydrocracking, andcatalytic hydroisomerisation. Group IV base stocks include for example,hydrogenated oligomers of alpha olefins.

A combination of properties is desirable in a base stock. In someinstances, for example in passenger car engine oils, it may be desirablefor a base stock to have a low viscosity profile, since this leads toimproved fuel economy. In particular, it is desirable for base stocks tohave a low kinematic viscosity as well as good low-temperature viscositycharacteristics, for example a low pour point or low viscosity asmeasured using a mini-rotary viscometer (MRV). However, the generaltrend is for an improvement in the viscosity profile (i.e. a reductionin viscosity parameters) of a base oil to be accompanied by anundesirable increase in volatility.

Accordingly, there is a need in the art for a base stock having adesirable viscosity profile, including good low-temperature viscositycharacteristics, but which also exhibits low volatility.

Problems may also be encountered when a base stock is incorporated intoa lubricating composition and used in an engine. For instance, poormiscibility of a base stock with lubricant additives or other basestocks may lead to problems in the engine, for instance with pistoncleanliness. Negative interactions between a base stock and oil sealsthat are found in engines may, in some cases, lead to loss of lubricantthrough failure of the oil seals. Base stocks may also undergo oxidativedegradation at the high temperatures encountered in an engine. Basestocks containing polar groups such as ester or other groups may beparticularly prone to at least some of these problems.

Accordingly, there is a need for a base stock having low volatility fora given viscosity profile, but which is also suitable for use, forexample, in a lubricating composition for an internal combustion engine.

SUMMARY

A compound of formula (1) is provided:

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon atom to which        they are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl;

-   -   R₆ is alkyl or    -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   p is 0, 1, 2 or 3; and    -   m and n are 0, 1, 2 or 3 provided that m is 0 when R₄ and R₅ are        H.

Compounds of formula (1) may be used as base stocks.

Also provided is a base oil comprising a compound of formula (1), aswell as a lubricant composition comprising said base oil.

Also provided are methods of preparing base oils and lubricantcompositions.

Also provided is a method for lubricating a surface using a lubricantcomposition, as well as the use of a lubricant composition forlubricating a surface.

Also provided are methods and uses of improving the oxidative stabilityperformance, fuel economy performance and/or piston cleanlinessperformance of a lubricating composition, and of improving the fueleconomy performance and/or piston cleanliness performance of an engineand/or vehicle.

DETAILED DESCRIPTION Ether Base Stocks

A compound of formula (1) is provided:

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon atom to which        they are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl;

-   -   R₆ is alkyl or    -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   p is 0, 1, 2 or 3; and    -   m and n are 0, 1, 2 or 3 provided that m is 0 when R₄ and R₅ are        H.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂alkyl or, together with the carbon atom to which they are attached,C₅₋₂₅ cycloalkyl.

In some embodiments, R₃, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H orC₂₋₁₂ alkyl. Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₂₀ alkyl or such as C₁₋₁₆ alkyl or

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, m and n are 0, 1 or 2, such as 0 or 1.

R₁ and R₂ are as described as alkyl or, together with the carbon atom towhich they are attached, cycloalkyl. It will be understood that, whereR₁ and R₂ are both alkyl groups, they may be the same as or differentfrom one another. Similar considerations apply to other substituentswhich are defined as part of a group of substituents. Thus, theconsiderations apply, for example, to R₃, R₄ and R₅; to R₇ and R₈; andto the values taken by m and n. For instance, where R₃, R₄ and R₅ aredescribed as being H or alkyl, it will be understood that each of R₃, R₄and R₅ may be H, each of R₃, R₄ and R₅ may be alkyl, or a subset of R₃,R₄ and R₅ may be H and a subset alkyl. Where R₃, R₄ and R₅, or a subsetthereof, are alkyl, each of R₃, R₄ and R₅ may be the same alkyl group orthey may be different alkyl groups. In contrast, where R₁ (or any othernotation) is used at a number of locations in a formula, it is used todenote the presence of the same group at each of these locations.

In each of the embodiments disclosed herein, the compounds may contain atotal number of carbons atoms of from about 20 to about 50. Forinstance, the total number of carbons in the compounds may be from about25 to about 45, such as from about 28 to about 40 or from about 30 toabout 36.

The alkyl and alkylene groups mentioned herein, i.e. those that may berepresented by R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉ and X, may be straightchain alkyl or alkylene groups, though they may also be branched. Insome embodiments, each alkyl group and each alkylene group contains asingle branch point or is a straight chain alkyl or alkylene group. Thealkyl and alkylene groups are preferably straight chain alkyl oralkylene groups. It will be understood that, aside from alkyl branching(if present), the alkyl and alkylene groups are unsubstituted and sothey do not contain any atoms other than carbon or hydrogen.

The cycloalkyl groups mentioned herein may contain a cyclopentyl,cyclohexyl or cycloheptyl group optionally having alkyl groups attachedthereto.

The compounds of formula (1) may have a kinematic viscosity at 40° C. ofless than about 25 cSt, such as less than about 20 cSt, or less thanabout 17 cSt. The compounds may have a kinematic viscosity at 100° C. ofless than about 7 cSt, such as less than about 5 cSt, or less than about4 cSt. The compounds may have a viscosity index of greater than about100, such as greater than about 110, or greater than about 120. Thekinematic viscosity at 40° C. and the kinematic viscosity at 100° C. maybe measured according to ASTM D7279. The viscosity index may be measuredaccording to ASTM D2270.

The compounds may have a Noack volatility of less than about 26%, suchas less than about 20%, less than about 16%, or less than about 12% byweight. Noack volatility may be measured according to CEC-L-40-A-93.

The compounds may have a viscosity at 150° C. and a shear rate of 10⁶s⁻¹ of no greater than 1.7 cP, such as no greater than 1.5 cP. This hightemperature high shear viscosity may be measured according toCEC-L-36-A-90.

The compounds may be used to improve the oxidative stability, fueleconomy performance and/or piston cleanliness performance of a lubricantcomposition, and/or the fuel economy performance and/or pistoncleanliness performance of an internal combustion engine and/or avehicle, such as an automotive vehicle associated with an internalcombustion engine. Accordingly, there are provided methods of improvingthe fuel economy performance and/or piston cleanliness performance of alubricant composition an internal combustion engine and/or a vehicle,such as an automotive vehicle associated with an internal combustionengine, comprising the step of providing or supplying to the lubricantcomposition, engine and/or vehicle at least one of the compounds.

The compounds may have a pour point of less than −10° C., such as lessthan about −25° C., or less than about −35° C. Pour point may bemeasured according to ASTM D5950.

The compounds may have a cold-crankcase simulator viscosity at −35° C.of less than about 1800 cP, such as less than about 1500 cP, or lessthan about 1200 cP, for example as measured according to ASTM D5293.

The compounds may have a DSC oxidation onset temperature of greater thanabout 165° C., such as greater than about 175° C., or greater than about185° C., for example as measured according to ASTM E2009 (method B).

In particular embodiments, the compounds of formula (1) may have akinematic viscosity at 100° C. of about 3 to about 4 cSt and a Noackvolatility of less than about 20%, such as less than about 16%, or lessthan about 12%, by weight; or a kinematic viscosity at 100° C. of about2 to about 3 cSt, and a Noack volatility of less than about 40%, such asless than about 30%, by weight.

The compounds of formula (1) are also particularly suited for blendinginto a lubricant composition. In particular, the compounds are misciblewith conventional base stocks, including hydrocarbon base stocks, aswell as with conventional lubricant additives. Moreover, the compoundsmay be used in a lubricant composition in a relatively high amount (forexample, in an amount of greater than about 10% by weight, such asgreater than about 20% by weight or greater than about 30% by weight)whilst meeting elastomer compatibility requirements for lubricantcompositions.

The compounds of formula (1) may be prepared from a wide range ofcommercially available feedstocks.

In some embodiments, the compounds are prepared from bio-derivedfeedstocks. For instance, the compounds may contain greater than about50%, such as greater than about 70%, or greater than about 90% by weightof biobased carbon. The biobased carbon content of the compounds may bemeasured according to ASTM D6866.

Guerbet-Derived Base Stocks

In preferred embodiments, the compounds of formula (1) are derived from(3-alkylated alcohols. In these embodiments, the compound may have theformula (2):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon atom to which        they are attached, cycloalkyl;    -   R₃ and R₅ are H or alkyl;    -   R₄ is alkyl;

-   -   R₆ is alkyl or    -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   p is 0, 1, 2 or 3; and    -   n is 0, 1, 2 or 3.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂alkyl or, together with the carbon atom to which they are attached,C₅₋₂₅ cycloalkyl. Preferably, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂alkyl.

In some embodiments, R₃ and R₅ are H or C₁₋₁₅ alkyl, such as H or C₂₋₁₂alkyl. Preferably, R₃ and R₅ are H.

In some embodiments, R₄ is C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In some embodiments, R₆ is C₁₋₁₅ alkyl or such as C₁₋₁₂ alkyl or

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, n is 0, 1 or 2, such as 0 or 1.

Where the compound is derived from a β-alkylated alcohol, it ispreferably derived, at least in part, from a Guerbet alcohol. Compoundswhich are derived, at least in part, from Guerbet alcohols may have theformula (3):

where:

-   -   R₁ is alkyl;    -   R₃ and R₅ are H or alkyl;    -   R₄ is alkyl;    -   R₆ is alkyl or

-   -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   p is 0, 1, 2 or 3; and    -   n is 0, 1, 2 or 3.

In some embodiments, R₁ is C₁₋₁₂ alkyl, such as C₂₋₁₀ alkyl.

In some embodiments, R₃ is H or C₁₋₁₂ alkyl, such as H or C₂₋₁₀ alkyl.Preferably, R₃ is H.

In some embodiments, R₄ is C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In some embodiments, R₅ is H or C₁₋₁₅ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₁₅ alkyl or

such as C₁₋₁₂ alkyl or

Preferably, R₆ is C₁₋₁₅ alkyl, such as C₁₋₁₂ alkyl.

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, n is 0, 1 or 2, such as 0 or 1.

One portion of the compound of formula (3) has a structure which may bederived from a Guerbet alcohol (i.e. the portion containing R₁ and R₃),whereas the other portion need not be derived from a Guerbet alcohol(i.e. the portion containing R₄, R₅ and R₆). However, in preferredembodiments, the compound may be derived from a combination of twoGuerbet alcohols. A compound prepared in this way may have the formula(4):

where:

-   -   R₁ and R₄ are alkyl;    -   R₃ and R₅ are H or alkyl.

In some embodiments, R₁ and R₄ are C₁₋₁₂ alkyl, such as C₂₋₁₀ alkyl.

In some embodiments, R₃ and R₅ are H or C₁₋₁₂ alkyl, such as H or C₂₋₁₀alkyl. Preferably, R₃ and R₅ are H.

In particular embodiments:

-   -   R₁ is C₄₋₁₂ alkyl, such as C₆₋₁₀ alkyl;    -   R₃ is H;    -   R₄ is C₁₋₁₀ alkyl, such as C₂₋₈ alkyl; and    -   R₅ is H.

Two different Guerbet alcohols may be combined to form compounds offormula (4), in which case R₁ and R₄ may be different. Alternatively, R₃and R₅ may be different. In some embodiments, R₁ and R₄ are differentand R₃ and R₅ are also different.

However, in some embodiments, the compound may be derived from areaction in which the same Guerbet alcohols are combined. A compoundprepared in this way may have the formula (5):

where:

-   -   R₁ is alkyl; and    -   R₃ is H or alkyl.

In some embodiments, R₁ is C₁₋₁₀ alkyl, such as C₂₋₉ alkyl.

In some embodiments, R₃ is H or C₁₋₉ alkyl, such as H or C₂₋₈ alkyl.Preferably, R₃ is H.

In particular embodiments:

-   -   R₁ is C₃₋₁₀ alkyl, such as C₄₋₈ alkyl; and    -   R₃ is H.

Compounds that are derived from Guerbet alcohols include compoundsGE1-GE3, GE5, GE7-GE9, SE1, SE2 and TE1 as shown in Table 3.

Guerbet alcohols may be prepared, for example, by dimerising primaryalcohols to form a β-alkylated alcohol product in a Guerbet reaction:

where R₁ and R₃ are as defined previously;and/or:

where R₄ and R₅ are as defined previously.

Guerbet reactions are well-known to the skilled person. The reactionsare typically carried out at elevated temperatures in the presence of acatalyst.

The compound may be prepared from the Guerbet alcohol, for example,according to the following reaction:

where:

-   -   Y is a leaving group; and    -   R₁, R₃, R₄, R₅, R₆ and n are as defined previously for the        compound of formula (3).

Where two Guerbet alcohols are combined to form a compound, one of theGuerbet alcohols may first be modified so that it contains a leavinggroup, Y, and the compound then prepared:

then:

or:

then:

where:

-   -   Y is a leaving group; and    -   R₁, R₃, R₄ and R₅ are as defined previously for the compound of        formula (4).

Where the same Guerbet alcohols are combined to form a compound, theymay be combined, for example, according to the following reactions:

then:

where:

-   -   Y is a leaving group; and    -   R₁ and R₃ are as defined previously for the compound of formula        (5).

Methods and reaction conditions for modifying a Guerbet alcohol so thatit contains a leaving group, Y, are known to the skilled person. Forinstance, a mesylate group may be introduced by reacting the Guerbetalcohol with mesyl chloride in the presence of triethylamine. A bromidegroup may be introduced by reacting the Guerbet alcohol withN-bromosuccinimide and triphenyl phosphine.

Methods and reaction conditions for carrying out etherificationreactions are known to the skilled person. A base (for example potassiumhydroxide or potassium tert-butoxide), a catalyst (for example Starks'catalyst: N-Methyl-N,N,N-trioctyloctan-1-ammonium chloride) or both maybe used in the abovementioned compound forming reactions, i.e. theetherification reactions.

In the abovementioned compound forming reactions, Y may be any suitableleaving group, such as a halogen (for example bromine, chlorine oriodine) or a sulfonate ester (for example mesylate or tosylate).

Secondary and Tertiary Ether Base Stocks

In some preferred embodiments, the compounds of formula (1) aresecondary or tertiary ether compounds. In these embodiments, thecompound may have the formula (6):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon to which they        are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl;    -   R₆ is alkyl or

-   -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   p is 0, 1, 2 or 3; and    -   n is 0, 1, 2 or 3.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂alkyl or, together with the carbon atom to which they are attached,C₅₋₂₅ cycloalkyl. Preferably, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂alkyl.

In some embodiments, R₃, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H orC₂₋₁₂ alkyl. Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₂₀ alkyl or

such as C₁₋₁₆ alkyl or

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, n is 0, 1 or 2, such as 0 or 1.

Secondary and tertiary ether compounds may have the formula (7):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon to which they        are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl; and    -   R₆ is alkyl.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂ alkylor, together with the carbon to which they are attached, C₅₋₂₅cycloalkyl.

In some embodiments, R₃, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H orC₂₋₁₂ alkyl. Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₂₀ alkyl, such as C₁₋₁₆ alkyl.

The compounds may be secondary ether compounds of formula (8):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon to which they        are attached, cycloalkyl;    -   R₄ and R₅ are H or alkyl; and    -   R₆ is alkyl.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In other embodiments, the secondary ether may be obtained from a cycliccompound. In this case, R₁ and R₂, together with the carbon to whichthey are attached, form a cycloalkyl group, such as a C₅₋₃₀ cycloalkylor a C₅₋₂₅ cycloalkyl. The cycloalkyl group may contain a cyclopentyl,cyclohexyl or cycloheptyl group optionally having one or more alkylgroups, such as C₁₋₁₂ alkyl or C₁₋₈ alkyl, attached thereto.

In some embodiments, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H or C₂₋₁₂alkyl. Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₂₀ alkyl, such as C₁₋₁₆ alkyl.

In particular embodiments:

-   -   R₁ and R₂ are C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl;    -   R₄ and R₅ are H; and    -   R₆ is C₄₋₂₀ alkyl, such as C₆₋₁₅ alkyl.

In other particular embodiments:

-   -   R₁ and R₂ are C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl;    -   R₄ is C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl;    -   R₅ is H; and    -   R₆ is C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl.

The compounds may be tertiary ether compounds of formula (9):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon to which they        are attached, cycloalkyl;    -   R₃ is alkyl;    -   R₄ and R₅ are H or alkyl; and    -   R₆ is alkyl.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂ alkylor, together with the carbon to which they are attached, C₅₋₂₅cycloalkyl. Preferably, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In some embodiments, R₃ is C₁₋₁₂ alkyl, such as C₁₋₁₀ alkyl.

In some embodiments, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H or C₂₋₁₂alkyl.

In some embodiments, R₆ is C₁₋₂₀ alkyl, such as C₁₋₁₆ alkyl.

In particular embodiments:

-   -   R₁ and R₂ are C₂₋₁₂ alkyl, such as C₄₋₁₀ alkyl;    -   R₃ is C₁₋₁₀ alkyl, such as C₁₋₈ alkyl;    -   R₄ and R₅ are H; and    -   R₆ is C₄₋₂₀ alkyl, such as C₆₋₁₅ alkyl.

In other particular embodiments:

-   -   R₁, R₂ and R₃ are C₂₋₁₂ alkyl, such as C₄₋₁₀ alkyl;    -   R₃ is C₁₋₁₀ alkyl, such as C₁₋₈ alkyl;    -   R₄ is C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl;    -   R₅ is H; and    -   R₆ is C₃₋₁₂ alkyl, such as C₅₋₁₀ alkyl.

Examples of secondary and tertiary ether compounds include SE1, SE2 andTE1 as shown in Table 3.

The secondary and tertiary ether compounds may be prepared according tothe following reactions:

or:

where:

-   -   Y is a leaving group; and    -   R₁, R₂, R₃, R₄, R₅, R₆ and n are as defined previously for the        compound of formula (6).

Similarly:

or:

where: Y is a leaving group; and

-   -   R₁, R₂, R₃, R₄, R₅ and R₆ are as defined previously for the        compound of formula (7).

The skilled person will be aware of methods and reaction conditions forcarrying out these etherification reactions. For instance, the reactionmay be carried out in the presence of magnesium sulfate, sulfuric acidand dichloromethane.

Secondary and tertiary alcohol starting materials for use inetherification reactions will generally be commercially available, orthey may be obtained from commercially available ketones.

The groups

may be prepared by introducing a leaving group, Y, into the alcoholstarting materials. Methods and reaction conditions for introducing theleaving group into alcohol are known to the skilled person.

In the abovementioned secondary and tertiary ether compound formingreactions, Y may be any suitable leaving group, such as a halogen (forexample bromine, chlorine or iodine) or a sulfonate ester (for examplemesylate or tosylate).

Secondary or Tertiary Ethers Derived from a Guerbet Alcohol

In some embodiments, the compound may comprise an ether which is derivedon one side from a secondary or tertiary alcohol and is derived on theother side from a Guerbet alcohol. In these embodiments, the compoundmay have the formula (10):

where:

-   -   R₁ and R₄ are alkyl;    -   R₃ and R₅ are H or alkyl;    -   R₆ is alkyl or

-   -   where:        -   R₇ and R₈ are H, alkyl or, together with the carbon atom to            which they are attached, cycloalkyl;        -   R₉ is H or alkyl;        -   X is alkylene or is absent; and        -   and p is 0, 1, 2 or 3.

In some embodiments, R₁ is C₁₋₁₂ alkyl, such as C₂₋₁₀ alkyl.

In some embodiments, R₃ is H or C₁₋₁₂ alkyl, such as H or C₂₋₁₀ alkyl.Preferably, R₃ is H.

In some embodiments, R₄ is C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In some embodiments, R₅ is H or C₁₋₁₅ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₅ is H.

In some embodiments, R₆ is C₁₋₁₅ alkyl or such as C₁₋₁₂ alkyl or

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

Examples of secondary and tertiary ether compounds derived from aGuerbet-alcohol include compounds SE1, SE2 and TE1 as shown in Table 3.

Di-Ether Base Stocks

It is generally preferred that the compounds of formula (1) aremonoethers. However, in some embodiments, the compound is a diethercompound. Such compounds may have the formula (11):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon atom to which        they are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl;    -   R₇ and R₈ are H, alkyl or, together with the carbon atom to        which they are attached, cycloalkyl;    -   R₉ is H or alkyl;    -   X is alkylene or is absent;    -   p is 0, 1, 2 or 3; and    -   m and n are 0, 1, 2 or 3.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂ alkylor, together with the carbon to which they are attached, C₅₋₂₅cycloalkyl. Preferably, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂ alkyl.

In some embodiments, R₃, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H orC₂₋₁₂ alkyl. Preferably, R₃ and R₅ are H.

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, m and n are 0, 1 or 2, such as 0 or 1.

In some embodiments, the diether compound may contain two ether groups,at least one of which is derived from a β-alkylated alcohol. In suchembodiments, the compound may have the formula (12):

where:

-   -   R₁ and R₂ are alkyl or, together with the carbon atom to which        they are attached, cycloalkyl;    -   R₃, R₄ and R₅ are H or alkyl;    -   R₇ and R₈ are H, alkyl or, together with the carbon atom to        which they are attached, cycloalkyl;    -   R₉ is H or alkyl;    -   X is alkylene or is absent;    -   p is 0, 1, 2 or 3; and    -   n is 0, 1, 2 or 3.

In some embodiments, R₁ and R₂ are C₁₋₁₅ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as C₂₋₁₂alkyl or, together with the carbon atom to which they are attached,C₅₋₂₅ cycloalkyl. Preferably, R₁ and R₂ are C₁₋₁₅ alkyl, such as C₂₋₁₂alkyl.

In some embodiments, R₃, R₄ and R₅ are H or C₁₋₁₅ alkyl, such as H orC₂₋₁₂ alkyl. Preferably, R₃ and R₅ are H. Preferably, R₄ is C₁₋₁₅ alkyl,such as C₂₋₁₂ alkyl

In some embodiments, R₇ and R₈ are H, C₁₋₂₀ alkyl or, together with thecarbon atom to which they are attached, C₅₋₃₀ cycloalkyl, such as H,C₂₋₁₂ alkyl or, together with the carbon atom to which they areattached, C₅₋₂₅ cycloalkyl. Preferably, R₇ and R₈ are C₁₋₂₀ alkyl, suchas C₂₋₁₂ alkyl.

In some embodiments, R₉ is H or C₁₋₂₀ alkyl, such as H or C₂₋₁₂ alkyl.Preferably, R₉ is H.

In some embodiments, X is C₁₋₂₀ alkylene, such as C₃₋₁₅ alkylene.

In some embodiments, p is 0, 1 or 2, such as 0 or 1.

In some embodiments, n is 0, 1 or 2, such as 0 or 1.

Base Oils and Lubricant Compositions

The compounds of formula (1) may be used as part of a base oil.

The base oils may contain an amount of compound of formula (1) which issufficient to impart beneficial properties of the compound onto the baseoil.

In some embodiments, the base oil comprises greater than about 5%, suchas greater than about 25%, or greater than about 40% by weight ofcompound of formula (1). The base oil may comprise up to about 100%,such as up to about 90% of compound of formula (1). The compound offormula (1) in the base oil may be composed of a single compound or acombination of compounds of formula (1).

The remainder of the base oil may be made up with base stocks which arenot compounds of formula (1). Base stocks other than those of formula(1) which are suitable for use in the base oil include non-aqueous basestocks, such as Group I, Group II, Group III, Group IV and Group V basestocks. The remainder of the base oil may comprise a single base stockor a combination of base stocks other than those of formula (1).

The base oils may be used as part of a lubricant composition.

The lubricant compositions may contain an amount of base oil which issufficient to impart beneficial properties of the compound of formula(1) onto the lubricating composition.

In some embodiments, the lubricant composition comprises greater thanabout 50%, such as greater than about 65%, or greater than about 80% byweight of base oil. The base oil may be composed of a single base oil ora combination of base oils comprising compound of formula (1).

The lubricant composition may also comprise lubricant additives. Thelubricant composition may comprise a single lubricant additive, thoughit will typically comprise a combination of lubricant additives. Thelubricant additives will typically be present in the lubricantcomposition in an amount of from about 5% to about 40% by weight, suchas about 10% to about 30% by weight.

Suitable lubricant additives include detergents (including metallic andnon-metallic detergents), friction modifiers, dispersants (includingmetallic and non-metallic dispersants), viscosity modifiers, dispersantviscosity modifiers, viscosity index improvers, pour point depressants,anti-wear additives, rust inhibitors, corrosion inhibitors, antioxidants(sometimes also called oxidation inhibitors), anti-foams (sometimes alsocalled anti-foaming agents), seal swell agents (sometimes also calledseal compatibility agents), extreme pressure additives (includingmetallic, non-metallic, phosphorus containing, non-phosphoruscontaining, sulphur containing and non-sulphur containing extremepressure additives), surfactants, demulsifiers, anti-seizure agents, waxmodifiers, lubricity agents, anti-staining agents, chromophoric agents,metal deactivators, and mixtures of two or more thereof.

In some embodiments, the lubricant composition comprises a detergent.Examples of detergents include ashless detergents (that is, non-metalcontaining detergents) and metal-containing detergents. Suitablenon-metallic detergents are described for example in U.S. Pat. No.7,622,431. Metal-containing detergents comprise at least one metal saltof at least one organic acid, which is called soap or surfactant.Suitable organic acids include for example, sulphonic acids, phenols(suitably sulphurised and including for example, phenols with more thanone hydroxyl group, phenols with fused aromatic rings, phenols whichhave been modified for example, alkylene bridged phenols, and Mannichbase-condensed phenols and saligenin-type phenols, produced for exampleby reaction of phenol and an aldehyde under basic conditions) andsulphurised derivatives thereof, and carboxylic acids including forexample, aromatic carboxylic acids (for example hydrocarbyl-substitutedsalicylic acids and derivatives thereof, for example hydrocarbylsubstituted salicylic acids and sulphurised derivatives thereof).

In some embodiments, the lubricant composition comprises a frictionmodifier. Suitable friction modifiers include for example, ash-producingadditives and ashless additives. Examples of suitable friction modifiersinclude fatty acid derivatives including for example, fatty acid esters,amides, amines, and ethoxylated amines. Examples of suitable esterfriction modifiers include esters of glycerol for example, mono-, di-,and tri-oleates, mono-palmitates and mono-myristates. A particularlysuitable fatty acid ester friction modifier is glycerol monooleate.Examples of suitable friction modifiers also include molybdenumcompounds for example, organo molybdenum compounds, molybdenumdialkyldithiocarbamates, molybdenum dialkylthiophosphates, molybdenumdisulphide, tri-molybdenum cluster dialkyldithiocarbamates, non-sulphurmolybdenum compounds and the like. Suitable molybdenum-containingcompounds are described for example, in EP 1533362 A1 for example inparagraphs [0101] to [0117].

In some embodiments, the lubricant composition comprises a dispersant.Examples of suitable ashless dispersants include oil soluble salts,esters, amino-esters, amides, imides and oxazolines of long chainhydrocarbon-substituted mono- and polycarboxylic acids or anhydridesthereof; thiocarboxylate derivatives of long chain hydrocarbons; longchain aliphatic hydrocarbons containing polyamine moieties attacheddirectly thereto; Mannich condensation products formed by condensing along chain substituted phenol with formaldehyde and polyalkylenepolyamine; Koch reaction products and the like.

In some embodiments, the lubricant composition comprises a dispersantviscosity modifier. Examples of suitable dispersant viscosity modifiersand methods of making them are described in WO 99/21902, WO 2003/099890and WO 2006/099250.

In some embodiments, the lubricant composition comprises a viscosityindex improver. Examples of suitable viscosity modifiers include highmolecular weight hydrocarbon polymers (for example polyisobutylene,copolymers of ethylene and propylene and higher alpha-olefins);polyesters (for example polymethacrylates); hydrogenatedpoly(styrene-co-butadiene or isoprene) polymers and modifications (forexample star polymers); and esterified poly(styrene-co-maleic anhydride)polymers. Oil-soluble viscosity modifying polymers generally exhibitnumber average molecular weights of at least about 15000 to about1000000, such as about 20000 to about 600000 as determined by gelpermeation chromatography or light scattering methods.

In some embodiments, the lubricant composition comprises a pour pointdepressant. Examples of suitable pour point depressants include C₈ toC₁₈ dialkyl fumarate/vinyl acetate copolymers, methacrylates,polyacrylates, polyarylamides, polymethacrylates, polyalkylmethacrylates, vinyl fumarates, styrene esters, condensation products ofhaloparaffin waxes and aromatic compounds, vinyl carboxylate polymers,terpolymers of dialkyfumarates, vinyl esters of fatty acids and allylvinyl ethers, wax naphthalene and the like. In at least some examples,the at least one lubricant additive includes at least one anti-wearadditive. Examples of suitable anti-wear additives includenon-phosphorus containing additives for example, sulphurised olefins.Examples of suitable anti-wear additives also includephosphorus-containing anti-wear additives. Examples of suitable ashlessphosphorus-containing anti-wear additives include trilauryl phosphiteand triphenylphosphorothionate and those disclosed in paragraph [0036]of US 2005/0198894. Examples of suitable ash-forming,phosphorus-containing anti-wear additives include dihydrocarbyldithiophosphate metal salts. Examples of suitable metals of thedihydrocarbyl dithiophosphate metal salts include alkali and alkalineearth metals, aluminium, lead, tin, molybdenum, manganese, nickel,copper and zinc. Particularly suitable dihydrocarbyl dithiophosphatemetal salts are zinc dihydrocarbyl dithiophosphates (ZDDP).

In some embodiments, the lubricant composition comprises a rustinhibitor. Examples of suitable rust inhibitors include non-ionicpolyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols,polyoxyalkylene polyols, anionic alky sulphonic acids, zincdithiophosphates, metal phenolates, basic metal sulphonates, fatty acidsand amines.

In some embodiments, the lubricant composition comprises a corrosioninhibitor. Examples of suitable corrosion inhibitors includephosphosulphurised hydrocarbons and the products obtained by thereaction of phosphosulphurised hydrocarbon with an alkaline earth metaloxide or hydroxide, non-ionic polyoxyalkylene polyols and estersthereof, polyoxyalkylene phenols, thiadiazoles, triazoles and anionicalkyl sulphonic acids. Examples of suitable epoxidised ester corrosioninhibitors are described in US 2006/0090393.

In some embodiments, the lubricant composition comprises an antioxidant.Examples of suitable antioxidants include alkylated diphenylamines,N-alkylated phenylenediamines, phenyl-a-naphthylamine, alkylatedphenyl-a-naphthylamines, dimethylquinolines, trimethyldihydroquinolinesand oligomeric compositions derived therefrom, hindered phenolics(including ashless (metal-free) phenolic compounds and neutral and basicmetal salts of certain phenolic compounds), aromatic amines (includingalkylated and non-alkylated aromatic amines), sulphurised alkyl phenolsand alkali and alkaline earth metal salts thereof, alkylatedhydroquinones, hydroxylated thiodiphenyl ethers, alkylidenebisphenols,thiopropionates, metallic dithiocarbamates, 1,3,4-dimercaptothiadiazoleand derivatives, oil soluble copper compounds (for example, copperdihydrocarbyl thio- or thio-phosphate, copper salts of a synthetic ornatural carboxylic acids, for example a C₈ to C₁₈ fatty acid, anunsaturated acid or a branched carboxylic acid, for example basic,neutral or acidic Cu(I) and/or Cu(II) salts derived from alkenylsuccinic acids or anhydrides), alkaline earth metal salts ofalkylphenolthioesters, suitably containing C₅ to C₁₂ alkyl side chains,calcium nonylphenol sulphide, barium t-octylphenyl sulphide,dioctylphenylamine, phosphosulphised or sulphurised hydrocarbons, oilsoluble phenates, oil soluble sulphurised phenates, calciumdodecylphenol sulphide, phosphosulphurised hydrocarbons, sulphurisedhydrocarbons, phosphorus esters, low sulphur peroxide decomposers andthe like.

In some embodiments, the lubricant composition comprises an antifoamagent. Examples of suitable anti-foam agents include silicones, organicpolymers, siloxanes (including poly siloxanes and (poly) dimethylsiloxanes, phenyl methyl siloxanes), acrylates and the like.

In some embodiments, the lubricant composition comprises a seal swellagent. Examples of suitable seal swell agents include long chain organicacids, organic phosphates, aromatic esters, aromatic hydrocarbons,esters (for example butylbenzyl phthalate) and polybutenyl succinicanhydride.

The lubricant composition may comprise lubricant additives in theamounts shown in Table 2.

TABLE 2 Lubricant composition Suitable amount (actives) if presentPreferred amount (actives) if present Additive type by weight by weightPhosphorus-containing Corresponding to about 10 to Corresponding toabout 10 to anti-wear additives about 6000 ppm P about 1000 ppm PMolybdenum-containing Corresponding to about 10 to Corresponding toabout 40 to anti-wear additives about 1000 ppm Mo about 600 ppm MoBoron-containing anti- Corresponding to about 10 to Corresponding toabout 50 to wear additives about 500 ppm B about 100 ppm B Frictionmodifiers About 0.01 to about 5% About 0.01 to about 1.5%Molybdenum-containing Corresponding to about 10 to Corresponding toabout 400 friction modifiers about 1000 ppm Mo to about 600 ppm MoDispersants About 0.1 to about 20% About 0.1 to about 8% DetergentsAbout 0.01 to about 6% About 0.01 to about 4% Viscosity index improversAbout 0.01 to about 20% About 0.01 to about 15% Pour point depressantsAbout 0.01 to about 5% About 0.01 to about 1.5% Corrosion and/or rustAbout 0.01 to about 5% About 0.01 to about 1.5% inhibitors Anti-oxidantsAbout 0.01 to about 10% About 0.5 to 5 about % Antifoams containingCorresponding to about 1 to Corresponding to about 1 to silicon about 20ppm Si about 10 ppm Si

The lubricant compositions may have a kinematic viscosity at 40° C. ofless than about 60 cSt, such as less than about 55 cSt, or less thanabout 50 cSt. The lubricant compositions may have a kinematic viscosityat 100° C. of less than about 12 cSt, such as less than about 10 cSt, orless than about 9.5 cSt. The lubricant compositions may have a viscosityindex of greater than about 100, such as greater than about 110, orgreater than about 120. The kinematic viscosity at 40° C. and thekinematic viscosity at 100° C. may be measured according to ASTM D445.The viscosity index may be calculated according to ASTM D2270.

The lubricant compositions may have a Noack volatility of less thanabout 25%, such as less than about 15%, or less than about 10% byweight. Noack volatility may be measured according to CEC-L-40-A-93.

The lubricant compositions may have a viscosity at 150° C. and a shearrate of 10⁶ s⁻¹ of no greater than 3 cP, such as no greater than 2.8 cP.This high temperature high shear viscosity may be measured according toCEC-L-36-A-90.

The lubricant composition may have at least one of:

an oxidative stability performance on a CEC-L-088-02 test indicated byan absolute viscosity increase at 40° C. of no more than 45 cSt, such asno more than 35 cSt or no more than 25 cSt; a fuel economy performanceon a CEC-L-054-96 test of at least 2.5%, such as at least 3%; and apiston cleanliness performance on a CEC-L-088-02 test indicated by anoverall piston merit of at least 8.5, such as 9.

The lubricant compositions may have a cold-crankcase simulatorperformance at −30° C. of less than about 3000, such as less than about2800, or less than about 2750, for example as measured according to ASTMD5293.

Preferred lubricant compositions meet the requirements set out in SAEJ300.

The lubricant compositions may be used in a method of lubricating asurface.

Suitable surfaces include those in power transmission systems forexample drive lines and gear boxes for example for vehicles includingfor example passenger vehicles and heavy duty vehicles; and those ininternal combustion engines, for example the crankcases of internalcombustion engines. Suitable surfaces also include those in turbinebearings for example in water turbine bearings.

Suitable internal combustion engines include, for example, engines usedin automotive applications, engines used in marine applications andengines used in land-based power generation plants. The lubricantcompositions are particularly suited to use in an automotive internalcombustion engine.

The lubricant compositions may be used to improve the fuel economyand/or piston cleanliness performance of an internal combustion engineand/or a vehicle, such as an automotive vehicle associated with aninternal combustion engine. Accordingly, there are provided methods ofimproving the fuel economy and/or piston cleanliness performance of aninternal combustion engine and/or a vehicle, such as an automotivevehicle associated with an internal combustion engine, comprising thestep of providing or supplying to the engine and/or vehicle at least oneof the lubricant compositions.

The invention will now be described with reference to the accompanyingfigures and examples, which are not limiting in nature, in which:

FIG. 1 is a graph of volatility against pour point for compounds offormula (1), other ether base stocks and conventional base stocks;

FIG. 2 is a graph of volatility against kinematic viscosity at 100° C.for compounds of formula (1), other ether base stocks and conventionalbase stocks;

FIG. 3 is a graph of volatility against cold-cranking simulatorperformance for compounds of formula (1) and conventional base stocks;

FIG. 4a is a graph of kinematic viscosity at 40° C. against time oflubricant compositions containing compounds of formula (1), aconventional hydrocarbon base stock and a farnesene-derived ether basestock during a TU-5 JP engine test;

FIG. 4b is a graph of absolute change in kinematic viscosity at 40° C.of lubricant compositions containing compounds of formula (1), aconventional hydrocarbon base stock and a farnesene-derived ether basestock during a TU-5 JP engine test; and

FIG. 5 is a graph of overall piston merit performance of lubricantcompositions containing compounds of formula (1) and a conventionalhydrocarbon base stock during a TU-5 JP engine test.

EXAMPLES Example 1—Properties of Ether Base Stocks

Guerbet-derived base stocks GE1-GE3, GE5 and GE7-GE9, secondary etherbase stocks SE1 and SE2, and tertiary ether base stock TE1 of formula(1) were prepared. Two further Guerbet-derived base stocks, GE4 and GE6,and an experimental group V base stock of the type previously describedin WO 2014/207235, i.e. a farnesene-derived ether base stock, were alsoprepared. The structure of these compounds is shown in Table 3.

TABLE 3 Molec- ular Chemical Weight Formula Structure GE1 466.87 C₃₂H₆₆O

GE2 466.87 C₃₂H₆₆O

GE3 522.97 C₃₆H₇₄O

GE4 466.87 C₃₂H₆₆O

GE5 410.76 C₂₈H₅₈O

GE6 466.87 C₃₂H₆₆O

GE7 522.57 C₃₆H₇₄O

GE8 382.42 C₂₆H₅₄O

GE9 466.51 C₃₂H₆₆O

GE10 410.76 C₂₈H₅₈O

GE12 382.71 C₂₆H₅₄O

GE14 410.76 C₂₈H₅₈O

GE15 354.65 C₂₄H₅₀O

GE16 424.79 C₂₉H₆₀O

GE18 438.81 C₃₀H₆₂O

GE20 354.65 C₂₄H₅₀O

GE21 382.71 C₂₆H₅₄O

GE22 410.76 C₂₈H₅₈O

GE23 382.71 C₂₆H₅₄O

SE1 452.84 C₃₁H₆₄O

SE2 396.43 C₂₇H₅₆O

TE1 466.87 C₃₂H₆₆O

Farnesene- derived ether 396.73 C₂₇H₅₆O

The following properties of the base stocks were tested:

Kinematic viscosity at 100° C. (KV100) and kinematic viscosity at 40° C.(KV40) were tested according to ASTM D7279.

Viscosity index (VI) was calculated according to ASTM D2270.

Pour point was determined according to ASTM D7346.

Differential scanning calorimetry (DSC) oxidation onset temperature wastested using a method which was based on ASTM E2009 (method B).According to the method, the base stocks were heated from 50° C. to 300°C., at a rate of 50° C./minute, under a pressure of 500 psi in analuminium SFI pan. The temperature at which an exotherm was observed wasrecorded.

Noack volatility was measured using a method which was based on IP 393and was considered similar to CEC-L-40-A-93. According to the method,reference oils of known Noack volatility were heated from 40° C. to 550°C. to determine the temperature at which the Noack volatility weightloss of each of the reference oils was reached. The base stocks weresubjected to the same process as the reference oils. The Noack weight ofthe base stocks could be determined based on the results obtained fromthe reference oils.

The results of the tests are summarized in Table 4, together withresults obtained from conventional base stocks (Durasyn 162, a group IVbase stock; Durasyn 164, a group IV base stock; Yubase 3, a group IIbase stock; Yubase 4, a group III base stock; Yubase 4 Plus, a group IIIbase stock; Nexbase 3020, a group II base stock; Nexbase 3030, a groupII base stock; Nexbase 3043, a group III base stock; and Chevron 100RLV,a group II base stock). Results obtained from the farnesene-derivedether base stock are also shown for reference.

TABLE 4 KV100 KV40 Pour Point DSC Oxidation Noack (cSt) (cSt) VI (° C.)Onset T (° C.) (% by weight) GE1 3.3 13.0 125 −42 201.26 5.9 GE2 3.513.7 145 −36 205.74 5.1 GE3 3.9 16.0 143 −42 202.89 2.4 GE4 3.3 11.9 146−27 213.37 3.9 GE5 2.5 8.2 136 −60 203.87 17.9 GE6 3.8 14.6 166 −12212.71 2.0 GE7 4.0 16.5 144 −36 206.26 6.8 GE8 2.3 7.7 111 −66 213.9544.9 GE9 3.8 14.9 160 −15 208.17 2.5 SE1 2.7 9.6 123 −18 195.37 12.9 SE22.5 9.0 101 −45 183.21 51.8 TE1 3.6 14.9 133 — 212.91 6.8 Durasyn 1621.7 5.2 92 −72 223.61 99.6 Durasyn 164 4.0 17.8 126 −75 221.31 18.8Yubase 3 3.0 14.1 105 −36 220.74 38.6 Yubase 4 4.2 19.2 126 −12 220.0011.7 Yubase 4 Plus 4.2 18.4 138 −18 220.32 11.6 Nexbase 3020 2.2 7.6 93−51 221.66 81.9 Nexbase 3030 3.0 12.0 101 −39 221.05 36.8 Nexbase 30434.3 19.9 124 −18 222.09 13.2 Chevron 4.6 22.6 119 −15 225.86 13.2 110RLVFarnesene- 3.2 11.6 152 −36 222.26 14.1 derived ether

A graph of volatility against pour point for ether base stocks GE1-GE9,SE1, SE2 and TE1 and the conventional base stocks is shown in FIG. 1. Itcan be seen that the Guerbet-derived base stock ethers have a lowvolatility for a given pour point compared to conventional base oils.Moreover, the Guerbet-derived base stocks in which both sides of theether are branched exhibit unexpected improvements in pour point ascompared to Guerbet-derived base stocks of comparable carbon number inwhich only one side of the ether is branched, without any significantloss of volatility.

A graph of volatility against kinematic viscosity at 100° C. for etherbase stocks GE1-GE9, SE1, SE2 and TE1 and the conventional base stocksis shown in FIG. 2. It can be seen that the Guerbet-derived base stocksand the secondary and tertiary ether base stocks exhibit both lowvolatility and low viscosity as compared to conventional base oils.

Cold-cranking simulator (CCS) analysis of Guerbet-derived base stocksGE2 and GE3 was also carried out according to ASTM D5293. A graph ofvolatility against cold-cranking simulator viscosity is shown in FIG. 3.For comparison, data obtained from conventional hydrocarbon base stockshaving a KV100 of from 2.6 to 4.2 is also shown. It can be seen that theGuerbet-derived ethers exhibit excellent CCS viscosity, as well as lowvolatility.

Example 2: Properties of Lubricant Compositions Containing Ether BaseStocks

Guerbet-derived ether base stocks GE2 and GE3 were blended withconventional base oil additives (additive A, a commercially availableadditive package; additive B, a cold-flow improver; additive C, anoxidation inhibitor; and additive D, a viscosity index improver) andconventional base oils (Yubase 4, a group III base oil; and Yubase 6, agroup III base oil) to form lubricant blends. A Baseline blend and afarnesene-derived ether blend were also prepared. Yubase 4 was chosen asthe main component of the Baseline blend, since it exhibits a similarKV100 to Guerbet-derived ether base stock, GE3. The Baseline blend wasbelieved to be a stringent baseline for comparison, since it is a 5W-30formulation which meets certain specifications (ACEA A5/B5,API-SN/GF-4). The details of the blended compositions are shown in Table5 in % by weight.

TABLE 5 Baseline GE2 GE3 Farnesene- blend blend blend derived blendAdditive A 16.4 16.4 16.4 16.4 Additive B 0.15 0.15 0.15 0.15 Additive C0.1 0.1 0.1 0.1 Additive D 4 4 4 4 Yubase 4 67.45 30.47 17.45 17.45Yubase 6 11.9 11.9 11.9 11.9 GE2 0 36.98 0 0 GE3 0 0 50 0Farnesene-derived ether 0 0 0 50

No problems with miscibility were encountered during preparation of theblended compositions.

The blended compositions were tested to see whether the advantageousproperties of the base stocks would be reflected in a fully formulatedlubricant composition. The following properties were tested:

Kinematic viscosity at 100° C. (KV100) and kinematic viscosity at 40° C.(KV40) were tested according to ASTM D445 (part of SAE J300).

Viscosity index (VI) was calculated according to ASTM D2270.

Cold-cranking simulator (CCS) analysis was carried out at −30° C.according to ASTM D5293 (part of SAE J300).

High temperature high shear (HTHS) analysis was carried out according toCEC-L-36-A-90.

Total base number (TBN) was determined according to ASTM D2896.

Noack volatility was tested according to CEC-L-40-A-93.

Sulphated ash content was measured according to IP 163.

The results of the tests are summarized in Table 6.

TABLE 6 Baseline GE2 GE3 Farnesene- blend blend blend derived blend KV40(cSt) 53.59 48.26 44.63 38.57 KV100 (cSt) 9.542 9.105 8.688 7.877 VI 164173 177 181 CCS −30° C. (cP) 4656 2608 2702 2010 HTHS (cP) 2.98 2.852.75 2.62 TBN (mg KOH/g) 11.66 11.29 11.44 10.88 NOACK (% by weight)11.2 7.7 9.7 14.9 Sulphated ash (%) 1.22 1.26 1.27 1.20

It can be seen that the properties of the Guerbet-derived base stocksare also exhibited in the blended compositions. In particular,beneficial viscosity, volatility and cold-flow properties are observed.The Guerbet-derived base stocks also exhibited similar HTHSmeasurements, TBNs and sulphated ash contents to the Baseline blend.

Example 3: Engine Performance of Lubricant Compositions Containing EtherBase Stocks

The blended compositions from Example 2 were subjected to a TU-5 JPengine test run according to CEC-L-88-02 (part of ACEA A, B and Csequences) in order to determine the oxidative stability of thecompositions by assessment of viscosity increases, as well as pistoncleanliness and piston ring sticking. The temperature in the oil gallerywas controlled to 150° C. for the duration of the test. The results ofthe TU-5 JP engine tests for the Baseline, GE2 and GE3 lubricantcompositions are shown in Table 7.

The blended compositions from Example 2 were also subjected to MRVtesting at −35° C. according to ASTM D4684 in order to gaugelow-temperature viscosity characteristics of the compositions before andafter use in the TU-5 JP engine test. The results of the MRV testing arealso shown in Table 7.

TABLE 7 Baseline GE2 GE3 Limits Absolute viscosity increase 47.3 27 13.1≤57.3 at 40° C. (mm²/s) Viscosity at 40° C. 53.8 45.1 48.2 None 0 hours(mm²/s) Viscosity at 40° C. 101.1 72.1 61.3 None 72 hours (mm²/s)Overall piston merit (x/10) 8.2 9.2 9.0 ≥7.6 (5 elements, CRC rating)Ring sticking merit 1st ring 10 10 10 ≥9 (worst) MRV pre-TU-5 (cP) 215007200 7500 Yield stress pre-TU-5 (Pa) <35 <35 <35 MRV post-TU-5 (cP)56500 11700 18000 Yield stress post-TU-5 (Pa) <35 <35 <35

The lubricant compositions containing Guerbet-derived base stocks passedall aspects of the TU-5 JP engine test.

A graph of kinematic viscosity at 40° C. against time is shown in FIG.4a , and a graph showing the absolute change in kinematic viscosity at40° C. after 60 hours is shown in FIG. 4b . For comparison, resultsobtained from the Farnesene-derived blend from Example 2 are also shown.It can be seen that the increase in viscosity of the lubricantcompositions containing Guerbet-derived base stocks or theFarnesene-derived blend were significantly lower than or similar to thatof the Baseline composition, with the results obtained from theGuerbet-derived ether being particularly good. The results indicate thatthe lubricant compositions containing ether base stocks exhibit superioroxidative stability.

A graph showing the overall piston merit is shown in FIG. 5. It can beseen that the lubricant compositions containing Guerbet-derived basestocks had overall high piston merits score, indicating that theseblends exhibit good piston cleanliness performance.

The MRV results further demonstrate the excellent low-temperatureviscosity characteristics of lubricant compositions containingGuerbet-derived base stocks before and after their use.

Example 4: Engine Compatibility of Lubricant Compositions ContainingEther Base Stocks

The blended formulation of GE3 from Example 2 was subjected to MercedesEAM and ACEA RE2 seal tests (test methods VDA 675301 and CEC-L-39-96,respectively) to determine the compatibility of the ether base stockswith typical seals that are found in engines. An ethylene acrylic rubberis used in the EAM test, whilst an acrylic-based rubber is used in theRE2 test. The results of the Mercedes EAM and ACEA RE2 seal tests areshown in Table 8.

TABLE 8 Baseline GE3 Pass Limits AEM Seal Tensile strength 9.5 3.4 > −35Test (Mpa % variation) Elongation Rupture −18.6 −26.9 > −50 (%variation) Hardness 3 5 10 to −5 (Variation, points) Relative volumechange 2.5 0.3 15 to −5 (%) ACEA Tensile Strength 2 2 18 to −15 RE2 (%variation) Elongation Rupture −32 −35 10 to −35 (% variation) Hardness 73 8 to −5 (Variation, points) Relative volume change 0.6 0.6 5 to −7 (%)

It can be seen that the lubricant composition containing aGuerbet-derived base stock passed both of the seal tests, indicatingthat the ether base stocks are suitable for use in engines.

Example 5: Engine Fuel Consumption Performance of Lubricant CompositionsContaining Ether Base-Stocks

Another blended formulation of GE3 and the baseline blend were subjectedto an M111 fuel economy test according to CEC-L-054-96 (part of the ACEAA and B sequences) in order to determine the fuel consumptionperformance of engines run on ether base-stocks. The results are givenbelow in table 9 and are quoted as percentage improvement over the RL19115W-40 baseline oil commonly used for such assessments. Accordingly, theresults reported as “Baseline” below recite the percentage performanceof the Baseline blend (5W-30 formulation mentioned above) over the RL191 15W-40 standard.

TABLE 9 Baseline GE3 Pass Limits Fuel Economy 2.89% 3.19% >2.5%Improvement relative to RL191 15W-40

It can be seen that the lubricant containing a Guerbet-derived basestock passed the fuel economy test and showed an improvement over thebaseline lubricant composition, indicating that the ether base stocksoffer a fuel economy benefit.

1-33. (canceled)
 34. A compound of formula (2):

where: R₁ and R₂ are alkyl or, together with the carbon atom to whichthey are attached, cycloalkyl; R₃ and R₅ are H or alkyl; R₄ is alkyl; R₆is alkyl; and n is 0, 1, 2 or 3, wherein the compound contains a totalnumber of carbon atoms of from 20 to
 50. 35. The compound of claim 34,wherein the compound has the formula (3):

where: R₁ is alkyl; R₃ and R₅ are H or alkyl; R₄ is alkyl; R₆ is alkyl;and n is 0, 1, 2 or
 3. 36. The compound of claim 35, wherein thecompound has the formula (4):

where: R₁ and R₄ are C₁₋₁₅ alkyl; R₃ and R₅ are H or C₁₋₁₅ alkyl. 37.The compound of claim 36, wherein: R₁ is C₄₋₁₂ alkyl; R₃ is H; R₄ isC₁₋₁₀ alkyl; and R₅ is H.
 38. The compound of claim 34, wherein thecompound has the formula (10):

where: R₁ and R₄ are alkyl; R₃ and R₅ are H or alkyl; R₆ is alkyl. 39.The compound of claim 34, wherein R₁ and R₂ are C₁₋₁₅ alkyl or, togetherwith the carbon atom to which they are attached, C₅₋₃₀ cycloalkyl; R₃and R₅ are H or C₁₋₁₅ alkyl; R₄ is C₁₋₁₅ alkyl; R₆ is C₁₋₁₅ alkyl; and nis 0, 1, or
 2. 40. The compound of claim 34, wherein R₁ and R₂ are C₂₋₁₂alkyl or, together with the carbon atom to which they are attached,C₅₋₂₅ cycloalkyl; R₃ and R₅ are H or C₂₋₁₂ alkyl; R₄ is C₂₋₁₂ alkyl; R₆is C₂₋₁₂ alkyl; and n is 0, 1, or
 2. 41. The compound of claim 34,wherein R₁ and R₂ are C₂₋₁₂ alkyl or, together with the carbon atom towhich they are attached, C₅₋₂₅ cycloalkyl; R₃ is H or C₂₋₁₂ alkyl; R₄ isC₂₋₁₂ alkyl; R₅ is H; R₆ is C₂₋₁₂ alkyl; and n is 0 or
 1. 42. Thecompound of claim 36, wherein: R₁ is C₆₋₁₀ alkyl; R₃ is H; R₄ is C₂₋₈alkyl; and R₅ is H.
 43. The compound of claim 34, wherein the compoundis prepared from bio-derived feedstock.
 44. The compound of claim 34,wherein the compound contains greater than 50% by weight of biobasedcarbon.
 45. The compound of claim 34, wherein the compound has at leastone of: a kinematic viscosity at 40° C. of less than 25 cSt; a kinematicviscosity at 100° C. of less than 7 cSt; a viscosity index of greaterthan 100; a viscosity at 150° C. and a shear rate of 10⁶ s⁻¹ of nogreater than 1.7 cP; a Noack volatility of less than 26% by weight; anda pour point of less than −10° C.
 46. The compound of claim 34, whereinthe compound has a kinematic viscosity at 100° C. of 3 to 4 cSt and aNoack volatility of less than 20% by weight; or a kinematic viscosity at100° C. of 2 to 3 cSt, and a Noack volatility of less than 40% byweight.
 47. A base oil comprising a compound as defined in claim
 34. 48.The base oil of claim 47, wherein the base oil comprises greater than10% by weight of the compound.
 49. The base oil of claim 47, wherein thebase oil comprises a base stock selected from Group I, Group II, GroupIII, Group IV and Group V base stocks and mixtures thereof.
 50. Alubricant composition comprising a base oil as defined in claim
 47. 51.The lubricant composition of claim 47, wherein the lubricant compositioncomprises greater than 50% by weight of the base oil.
 52. The lubricantcomposition of claim 47, wherein the lubricant composition has at leastone of: a kinematic viscosity at 40° C. of less than 60 cSt; a kinematicviscosity at 100° C. of less than 12 cSt; a viscosity index of greaterthan 100; a viscosity at 150° C. and a shear rate of 10⁶ s⁻¹ of nogreater than 3 cP; and a Noack volatility of less than 25% by weight.53. A method of preparing a base oil, said method comprising providing acompound as defined in claim 34, and preparing a base oil comprisingsaid compound.
 54. A method of preparing a lubricant composition, saidmethod comprising providing a base oil as defined in claim 47, andblending the base oil with one or more lubricant additives to preparethe lubricant composition.
 55. A method of improving the oxidativestability performance, fuel economy performance, and/or pistoncleanliness performance of a lubricating composition, comprising thestep of providing to the lubricating composition a compound according toclaim
 34. 56. A method of improving the oxidative stability performance,fuel economy performance, and/or piston cleanliness performance of alubricating composition, comprising the step of providing to thelubricating composition a base oil according claim
 47. 57. A method oflubricating a surface, said method comprising supplying a lubricantcomposition as defined in claim 50 to said surface.